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Old Dec 10, 2008, 06:25 PM
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Build Log
Telos building thread with $10 VACUUM BAGGING SYSTEM Tutorial!!!

Ok… here we go!
This may go slow for a few days as I’m dealing with being sick as I continue producing kits, so please be patient… Also, there are MANY ways to vacuum bag wings... This system and tutorial is designed for the beginner, but has a valuable place in the arsenal of tools of the professional builder as well. At least two professional kit builders have asked for this after sharing with them how thy can provide vacuum bagged wings more easily and faster than with a single more expensive vacuum bagging system... As a comparison: My "professional" vacuum pump is a multi-cabon graphite rotary vaned monster pulling 29 inches of Mercury at 11cu ft/min... It will crush a gallon paint can in seconds! For most hobby applications, you just don't need that kind of power or need to pay between $600 and $1,800 (USD) for a pump like that.


To start, I’m putting together a “parts list” for the vacuum bagging system from pump construction to the actual bag (Hopefully, this will give you time to accumulate everything and provide me with a couple more days of rest to recuperate.)

(Please note: I have always used TWO of these independent systems on the same bag as a back up… not necessary, but sure helps me sleep at night knowing there is a redundant system sucking air out of the bag containing my expensive skinned foam core! The parts list will be enough to construct two independent systems!

Pumps:
I purchased these at Wal-Mart for around $6USD… I’ve seen these go for under $1 at rummage sales! I’ve seen “Silent Giant” pumps go for $12 to $29 and do not believe they are any better… in fact, I think I had problems getting them apart to use the pump inside… Just make sure that whatever pump you obtain, fits into the coffee can or paint can you are using. (One pump per single system.)

Cans:
A simple coffee can, or a paint can works fine… In this case, I’m using both and they are both 1qt size variety. (One can per single system)

Pump Base:
These are the square wood pieces under each can… anything like this will work… it just has to be big enough to support the can with a little lip around it… One of these is ½” thick Medium Density Fiberboard (MDF), the other is ¾” thick scrap plywood; both cut roughly 6” square. If you are using a melamine or Formica covered piece of wood, we’ll be scuffing it up real well to support gluing the cans on to them (later). (One base per single system)

Vinyl Tubing:
I purchased a 20’ roll of ¼” clear vinyl tubing that matches the nipple on the aquarium pump… You’ll also see in the photo a 25’ roll of ¼” polyethylene tubing… the clear vinyl works fine, I wanted to try using the polyethylene thinking it might be better… (We’ll find out!) (20’ is enough for two systems!)

Brass Tubing:
Just a foot in length is enough for two systems. 3/16” brass K&S tubing fits the inside diameter of both the vinyl and polyethylene tubing.

5 Minute Epox:
Any brand will do… This epoxy will be used for pump construction, NOT for gluing your skins to your cores!

Wire Rod:
.045” to .062” (1/16”) diameter music wire (K&S brand sold in 36” length works fine, thin wire coat hanger will also work!) This will be placed inside the flexible tubing to keep it straight once placed in the vacuum bag. (One rod per single system. lengths should match the core your are bagging. In the case of the Telos, 24" length is fine.)

Vacuum Bag Plastic:
Here’s where you could try all sorts of whatever is available… I have used 6mil painter’s plastic as well as 10mil polypropylene… I’d stay way from the 2 and 4 mil plastic… too fragile and it tends to wrinkle and fold up on itself under pressure (vacuum). While researching for this tutorial, I found some 10 mill clear vinyl used for window covering… This looks like it will end up being my favorite!) Right along side was a rigid clear plastic that looked much more like Mylar or Polycarbonate… DO NOT USE IT! You want the plastic to be fairly flexible; capable of contouring easily around whatever shape you will be vacuum bagging! The 10mil clear vinyl was about $1.75 per linear foot that measured 4’ across! Allow for 18” to 24” more in width of your chord and span of the wing core you will be bagging when the bag is folded over like a file folder. (Example: 24" core length X 12" chord width = 24" long x 24" wide PLUS 18" to 24" equals a final size of 48"X 36" (You can always trim it, you can’t always add length!It's cheap stuff, you'll want to make more bags later!)

Rope Caulk Weather Stripping.
This is a clay like material is formed in a roll and used to place along leaky windows… I found this one at Ace Hardware (Lowes and Home Depot had their own brands, same stuff). Ace Hardware salespeople had a hard time understanding what I was looking for but were very patient and figured it out right away. Both Lowes and Home Depot reps claimed they didn’t have it…! At Lowes, I found a knowledgeable salesman that helped me find it! He should be promoted to the “managerial” positions that were currently filled by the people saying “We don’t carry that”… Lesson: Don’t give up! Be flexible in what you are asking for, tell them you may not be using the right words… This stuff was found near the windows department and the foam sticky back rubber window sealing strips available in rolls… You want the CLAY-LIKE stuff! I took some photos of the correct item in the store (that claimed not to carry it! Lol!) The smaller package contained 30 feet which is enough to make MANY bags! ($3USD?) Available in different colors, color doesn't matter!)

Silicone Sealant:
I’ve put these systems together before without this stuff! Consider it a redundant back up if you’re willing to try it… I will be using this as I plan to use these systems over and over again as I return to my passion for building and flying RC aircraft.

Packaging Tape:
I included a photo of the “dispensing gun” this tape is usually associated with… The thicker, the stronger, the better… I’d stay away from the thin stuff some people use to cover their foam flying wings… It’s probably fine, but I’d prefer the thicker stuff… maybe the actual 3-M brand?

OK… I think that’s it!

In the next installment, we will begin construction of the “vacuum pump”.

Welcome to the "build"!
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Old Dec 10, 2008, 06:37 PM
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This is great! I actually DO have a pump like that from the days I had an aquarium! Its quite small, but if it can drive a good filter I guess it'll work for a vacuum. Eager to see the results!,
-Alex
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Old Dec 10, 2008, 06:48 PM
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Did you buy all of that at Ace Home-Center? There is one nearby here Ill see if I can go with my bike right now and see if they have the stuff.
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Old Dec 10, 2008, 06:49 PM
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Telos Information:

In case some of you stop by here first before learning about the Telos project, If you're interested in finding out how all of this came about, here's a link to the Telos Thread:

http://www.rcgroups.com/forums/showthread.php?t=955809

There are many other kits in the wings at this time, some still on the drawing board, some in various prototype stages, others, like the new "DaVinci" project, weeks away from Beta testing... For background on who I am, what' Iv'e been doing for the 20 years since the first release of the Telos Canard, here's a link to my website:

www.jareldesign.com

Thanks for stopping by!

Richard
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Old Dec 10, 2008, 07:06 PM
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Buying the materials in the "real world"

I went to three sources I figured would cover most everyone... The idea is that most of these materials are available at your local hardware store... If you think you found something "similar" but are unsure, please feel free to share here... The hope is that you don't "Have to" purchase the "exact" item... just something close that will suffice...

Overseas model builders may not have a "Lowes, or Home Depot or Ace Hardware... they might have a "Fred and Mary's" building supplies or hard goods country store... In reality, I would "think" that a clear plastic shower curtain might work for bagging material... the idea around the bag material is that it be affordable, readily available, flexible enough to be sucked around a foam core wing, capable of being glued together using packaging tape, silicone adhesive, Duct tape (yeah, that will work too!) and most importantly, the clay-like window caulking...

The "stickability" of the window caulking is most important... this stuff (window caulk) is "re-usable" and will allow the builder to seal up the opening of the bag (where we put the core in through and take out through) while at the same time, being capable of being re-sealed over and over again while sustaining a good tight seal...

Hope this helps...

remember: There are no "dumb" questions... EVER! If you don't understand, just ask... If anyone wants to chime in with a CONSTRUCTIVE answer, please feel free to....

(Example: many people will listen to someone talking and might not understand a word being used... Instead of living in fear of being "found out" to not knowing the word... I interrupt the person and ask: "Can you please define that word for me?" If they agree to, they are helping me to increase my vocabulary and at the same time getting the message that I think it's important to understand what they are trying to share with me... If they are sarcastic, negative or tell me to go look it up in a dictionary... Do I really care what that person was trying to share in the first place?...

Please, let's keep this thread positive and constructive... I'm hoping to learn something from some of you as well!

Although we might "dabble" in conversation regarding exotic composites like Carbon Fiber, Kevlar, S-Glass etc... I'm pretty much hoping that most of the arguments over what works best and for what purpose goes elsewhere...

Example... Is Carbon Fiber "Stronger"? Not really because we might be asking the wrong question... with regards to "impact", Kevlar is "stronger"... with regards to "Stiffness" Carbon Fiber is "Stiffer"... In the Telos fuselage, I use Bi-Directional (As many strands going in one directions with the same amount of strands running in a 90 degree patterned weave) Carbon Fiber.

The Carbon Fiber is brittle though (due in part to it's chemical make up and it's stiffness.. To protect it, I place it in the mold behind one thin layer of tight weave glass (Which also helps to produce the glass like surface) and then support it with an even thicker layer of glass, followed by a thin layer of glass... FOUR layers with Carbon Fiber sandwiched in between... Ask ten different model builders, you'll get ten different preferences as to what to use and in what order... for this thread, I'm only interested in sharing conceptual foundational information so you are equipped and empowered with a basic understanding of the materials...

Ok... enough for now...

"Whew"! (And we really haven't even started yet!)
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Old Dec 10, 2008, 07:15 PM
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My Mistake!

The weatherstrip cord pictured on the boxes are NOT the right stuff!

The coil shown out of the box IS the right stuff!

They look the same, but in reality, the stuff in the boxes is a single strand rope... The stuff we want is a wide band measuring 1" to 2" across (? exact width unimportant... wider is better)... This 'band" is molded using a die that leaves rope like impressions so that the customer can easily strip it to the desired width... we want it as wide as possible up to about 3" max (1" to 2" is fine although wider can offer a redundant width of seal (I'll explain later)

Thanks!

Richard
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Old Dec 10, 2008, 07:15 PM
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Just came back from a short trip to ACE. They have everything (including the caulking), except the plastic. Ill see if I can find this plastic somewhere else.
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Old Dec 10, 2008, 07:18 PM
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Wow!

That was quick!

Remember that the plastic does not have to be the same stuff I have pictured here... a clear shower curtain, a thick (6 Mil to 10 Mil plastic painter's drop cloth...) Be creative as you shop... Sales people are set up to sell you what you ask for... they probably have no idea that you use for their "delux" shower curtain is to build a 200MPH+ DS sailplane wing! LOL!
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Old Dec 10, 2008, 07:22 PM
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Just a little question... the plastic can be that stuff that gardeners use to wrap seedlings in, or cover greenhouses, the thick blue or black plastic stuff?
Caulking is for sealing the edges of the bag right?
BTW the ACE is 5 mins away on bike so I can go back and look for the plastic stuff.
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Old Dec 10, 2008, 07:40 PM
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Oh boy... I'm sure there are going to be LOTS of questions referring to black plastic, blue plastic, gardener's plastic... (Thanks for starting this kind of questioning so soon!)

This is where it may get frustrating, but at the same time, you may discover a cheaper, better, more readily available material that you can then share with the rest of us!

Here's a hint: (What I'd do Buy the rope caulking and take a piece with you (as well as some packaging tape) to where the plastic is in the store... stick it together and see what happens... does it stick readily? (Yes? Then this is good!) (Does the packaging tape stick but is easily pulled off? Yes? This is not good...

The reason for using a clear or translucent plastic is so that we can keep our eyes on what's going on inside the bag when we slip our cores with loose (but epoxy covered) skins and where are we placing our suction tubes, Is epoxy leaking out somewhere? Have our skins shifted off the cores? Has the bag sealed up on itself not allowing the vacuum pressure to be evenly distributed.... I would NOT use black or any other opaque plastic that does not allow you to see clearly what is going on in the bag... Theoretically, anything will work, but sooner or later, there will come a day when you wished you had used a clear bag!

I'm not sure what the gardener's plastic is... You want something that is flexible... if it makes noise when flicked, it's not what you want... if it makes noise when you crinkle it up into a ball... it's not what you want... a painters plastic drop sheet has no stiffness to it... Vinyl in 10Mil does not really have any stiffness to it... a 2 Mil piece of acetate or other rigid plastic is more like a rigid sheet of micro plywood in comparison... we want something that has a certain amount of "drape" to it... (Hard to share this kind of qualitative description in words or still photos... If this doesn't work, maybe a short video of several different plastics... (I am really hard up for time at the moment...)

I do hope this helps!

Richard
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Old Dec 10, 2008, 07:45 PM
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Caulking and sealing the bag...

The packaging tape and silicone will be used to seal two sides of the bag... (One side will just be folded over)...

The weatherstrip caulking, never dries up, retains it's "stickiness" and can be pulled apart... we will use this to temporarily seal that part of the bag that we we insert and remove our wing cores through... we will also use this clay-like/putty-like caulk to seal in our vacuum hoses!

No expensive fittings! Yeah!

Let me know if you still have questions and if you try something different than I have mentioned, please share it with us and remember to include photos of the packaging as well as what it's intended purpose was before it became a "main-stay in the aerospace world" LOL! (You may just discover the next standard in "Low-Tech Vacuum Bagging"!

Thanks!
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Old Dec 10, 2008, 08:02 PM
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One LAST item to buy:

(I hope!)

Please understand that I'm working to get through a pretty bad cold while I'm fabricating kits, keeping track of correspondence and trying to ship these kits out in a timely manner... A lot you (over at the Telos thread) have been more than kind and understanding... This kind of work load is just something I'm used to doing...

In the Motion Picture Industry, "Deadlines" for special effects props and miniatures meant just that: deliver or die! (long story)... I'm actually taking it easy (by my standards... at least I'm working on it...

OK... last item... a can of silicone spray... any brand...

The way we get around breather cloths and the like is to sand (scuff) the inside of the bag so that microscopic scratches allow air to move around freely, even when the bag is in contact with itself... Normally this would create pockets devoid of any vacuum pressure... The silicone spray is applied (carefully! protecting the strip along the opening where the caulking seals the bag!) to the inside of the bag... if any epoxy slips out from behind the wing skin, it will fall right off the bag... We only use a very small amount and wipe it with a paper towel so that the silicone does not transfer to the wing skin... Usually, this is a one time only spray and is just enough of a non-stick "contaminant" to protect the inside of the bag from epoxy spills/leaks...

Ok... now I think I need to go to bed... I said I was going to many hours ago on the Telos thread! Aaaack! (The sound the Martians made in "Mars Attacks")

Richard
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Old Dec 11, 2008, 09:44 AM
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Really good idea with the aquarium pump for the vac source. I am impressed! Any idea how much vac it pulls? I have seen "deep water" aquarium pumps that may even pull more vacuum. They are a bit more expensive and less common so that may be getting away from the point of your contraption though. I imagine that even if this thing pulls just a tiny bit, it would be the equivalent of many books stacked on the top of wing shucks. I bet the DLG guys would be interested as well, especially for doing tail surfaces.
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Old Dec 11, 2008, 10:51 AM
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Really, you can pull any vacuum with an aquarium pump that size? I was thinking maybe 1-2mm Hg. It would be awesome if it works!

M.
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